camara circling around an object

In the past before 2.6 I used to select the camera first then shift select the path, in my case a circle or a bezier curve the shift p to select follow path.
Then I placed a constraint trackto to point to the object
Now whatever I do I can’t get the camera circling around the object following the curve or path?
Can somebody clear me out on this
I am using release 2.65 r53505 on win7

Just did it in 2.65 Added a curve (circle) Select the camera, shift select the path, ctrl+p select follow path. Then place the camera on the path.

Add an empty in the center of the circle, select the camera, add a track to constraint, select the circle path, and choose the correct axis (probably up=y to=-z)

Not select the path and change the evaluation time.

it is the whole morning I messed with that simple question.
I do not use an empty but directly the object that the camera will circle around
It works now but regarding finding out the axis. What is the correct way to know or find out which axis to select in the menu?
Just to understand how that works and not do things like trying without knowing.
Thanks again

You can turn the axis on and off in the display section section